Various systems are known in which a generator is driven by an engine, such as vehicles, boats and portable generators. In these systems, a battery is charged with electric power generated by the generator, and the engine is started by electric power supplied from the battery. However, where the battery has been completely discharged or its capacity has been lowered, there may be cases where the generator is driven by use of a human-power starting device such as a recoil starter and a kick device, and the engine is started by the power generation output of the generator.
Japanese Patent Laid-open No. 2004-282831 describes an electric power supply system for a vehicle in which a kick starter is provided as a human-power starting device. This electric power supply system is so configured that when the battery is in an abnormal condition, a battery control relay and a load control relay are turned OFF, and then a kicking operation for starting the engine is conducted. With the battery control relay and the load control relay turned OFF, the electric power generated by the kicking operation can be prevented from being exhausted in the form of a flow of current to the battery or other loads irrelevant to the starting of the engine. The electric power is supplied preferentially to a fuel supply system, an ignition system and the like indispensable for driving the engine.
The electric power supply system for a vehicle described in Japanese Patent Laid-open No. 2004-282831 has a configuration in which a control relay capable of selecting the part(s) to be supplied with electric power generated so as to inhibit the charging of the battery at the time of starting, for example, is provided in order to secure an engine starting performance during starting of the engine by the kick starter. However, such a control relay is not needed in a vehicle that does not include a kick starter, a recoil starter or the like. There may be cases where, for example, vehicles of the same model differ in specifications according to their destinations, and some of them have a recoil starter but others of them do not have a recoil starter. In manufacturing such vehicles, it is troublesome to separately produce circuit boards including a control relay and circuit boards not including the control relay, on the basis of each vehicle. In view of this, it is desired to facilitate the separate manufacturing of vehicles having a control relay and vehicles not having the control relay.